Slowing climate change by targeting gases other than carbon dioxide

Aug 03, 2011

Carbon dioxide remains the undisputed king of recent climate change, but other greenhouse gases measurably contribute to the problem. A new study, conducted by NOAA scientists and published online today in Nature, shows that cutting emissions of those other gases could slow changes in climate that are expected in the future.

Discussions with colleagues around the time of the 2009 United Nations' climate conference in Copenhagen inspired three NOAA scientists  Stephen Montzka, Ed Dlugokencky and James Butler of NOAA's Earth System Research Laboratory in Boulder, Colo.  to review the sources of non-carbon dioxide (CO2) greenhouse gases and explore the potential climate benefits of cutting their emissions.

Like CO2, other greenhouse gases trap heat in Earth's atmosphere. Some of these chemicals have shorter lifetimes than CO2 in the atmosphere. Therefore cutting emissions would quickly reduce their direct radiative forcing  a measure of warming influence.

"We know that recent climate change is primarily driven by carbon dioxide emitted during fossil-fuel combustion, and we know that this problem is going to be with us a long-time because carbon dioxide is so persistent in the atmosphere," Montzka said. "But lowering emissions of greenhouse gases other than carbon dioxide could lead to some rapid changes for the better."

Scientists know that stabilizing the warming effect of CO2 in the atmosphere would require a decrease of about 80 percent in human-caused CO2 emissions  in part because some of the carbon dioxide emitted today will remain in the atmosphere for thousands of years. In contrast, cutting all long-lived non-CO2 greenhouse gas emissions by 80 percent could diminish their climate warming effect substantially within a couple of decades. Cutting both CO2 and non-CO2 greenhouse gas emissions to this extent could result in a decrease in the total warming effect from these greenhouse gases this century, the new paper shows.

For the new analysis, the researchers considered methane; nitrous oxide; a group of chemicals regulated by an international treaty to protect Earth's ozone layer; and a few other extremely long-lived greenhouse gases currently present at very low concentrations.

The new review paper describes the major human activities responsible for these emissions, and notes that steep cuts (such as 80 percent) would be difficult. Without substantial changes to human behavior, emissions of the non-CO2 greenhouse gases are expected to continue to increase.

The climate-related benefits of reductions in non-CO2 greenhouse gases have limits, Montzka and his colleagues showed. Even if all human-related, non-CO2 greenhouse gas emissions could be eliminated today, it would not be enough to stabilize the warming influence from all greenhouse gases over the next 40 years  unless CO2 emissions were also cut significantly.

The scientists also noted in the paper the complicated connections between climate and greenhouse gases, some of which are not yet fully understood. The non-CO2 gases studied have natural sources as well as human emissions, and climate change could amplify or dampen some of those natural processes, Dlugokencky said. Increasingly warm and dry conditions in the Arctic, for example, could thaw permafrost and increase the frequency of wildfires, both of which would send more methane and carbon dioxide into the atmosphere.

"The long-term necessity of cutting carbon dioxide emissions shouldn't diminish the effectiveness of short-term action. This paper shows there are other opportunities to influence the trajectory of climate change," Butler said. "Managing emissions of non-carbon dioxide gases is clearly an opportunity to make additional contributions."

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User comments : 3

So the basis for Greenhouse gases contributing to global warming is supposedly the 1896 Arrhenius paper, where he concluded that "if the quantity of carbonic acid (CO2) increases in geometric progression, the augmentation of the temperature will increase nearly in arithmetic progression." which has led to the IPCC mantra thet "more GHGs means more warming."BUT how is it that when you look at Arrhenius's conclusion you find that whenever the amount of energy photons decreases (as in every night), that the temperature goes down IN SPITE of Arrhenius' conclusion, while CO2 goes up completely contradicting his conclusion. Could it really be that his conclusion should read that "More energy photons means more warming"? So that when we add more energy every morning it warms, when Mother Nature takes away the energy every night it cools.

Could it be that the assumption that CO2 "Traps" the photon energy & with its long life in the air we get a wrong conclusion that CO2 results in warming

These press releases have nothing to do with climate change, temperature or ecology. I'd like to see Physorg stop publishing this unsubstantiated ideological garbage.

The whole concept of a carbon "cap" is a phantom entity created by governments influenced by financial factions and their institutional policy organs.

The only thing a carbon "cap" does is allow the monetazation of carbon emissions, which are ubiquitous in human industry. It grants them the power to skim the fruit of all human activity into the bowls of the rulers and their financial masters.

Resist these attempts to corrupt scientific integrity and dismantle the remaining nation-states whose traditions of rational liberty threaten these parasites.

These ridiculously exaggerated claims are published to generate confusion and panic and to promote their creators as authorities and saviors. Reject them and demand calm, rational detachment as we consider the future with fairness for all.

When I can't get past the fifth word of the article without spotting opinion presented as fact, is there any point in reading further?

but other greenhouse gases measurably contribute to the problem

I guess it was foolish to keep reading. I've never seen anyone credible make the claim that statistically significant measurement of climate change and subsequent attribution to any one source is possible at this point. I would like to see a peer reviewed source that quantifies the climate change effect of other GHG's over the past century. I think they're making a bogus claim here.

It would be accurate to say that other GHG's theoretically should have contributed significantly to climate change in the past century, but to say that's it's measurable isn't supported by mainstream litterature.

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